Electric switch



Feb. 12, 1952 E. E. NoYl-:s 2,585,824

ELECTRIC SWITCH Filed Jan. 27, 1948 "l I x l Vl I INVENTOR.

I 1 fl/fRETT E. No vi BY 24 voga/WM Patented Feb. 12, 1952 ELECTRICSWITCH Everett E. Noyes, Warrensville, Ohio, assignor to The ElectricController & Manufacturing Company, Cleveland, Ohio, a corporation ofOhio Application January 27, 1948, Serial No. 4,569

20 Claims. 1

This invention relates to electric switches and more particularly toauxiliary or control circuit switches for use on electromagneticccntactors.

Electromagnetic contactors having main contacts which carry the loadcurrent of the translating device being controlled are often providedwith one or more auxiliary or control circuit switches. The auxiliaryswitches, which may have either normally-open or normally-closeicontacts or both, are interposed in the control circuits of thecontroller comprising the ccntactor or in the control circuits of arelated controller and generally serve an interlocking function toinsure a desired sequence of contactor operation. Since the proper andsafe operation of a complete control installation is dependent upon theability of the control circuit switches to function repeatedly in areliable and accurate manner, they must be rugged enough to withstandfor long periods of time the mechanical and electrical abuse to whichthey are often subjected. On the other hand, the control circuitswitches must be of limited size and require but a small amount of powerfor operation in order to maintain the overall size of the contactorwithin reasonable limits. Furthermore, the wearing parts of the controlcircuit switches should be easy to remove and replace and but a fewdifferent types of parts should be required for switches usable on manydifferent sizes of both normallyopen and normally-closed contactors.

It is the object of the present invention to provide an improved controlcircuit switch meeting all of the foregoing requirements.

Other objects are to provide an improved control circuit switch for useon electromagnetic contactors which requires no adjustment, hasnonhorizontal contact surfaces, has both normally open andnormally-closed double-break contacts, and is so arranged that itsvarious parts may be easily removed and replaced.

Another object is to provide an improved bridge-type control circuitswitch in which the movable normally-closed and normally-open contactbridges are completely insulated from each other.

An additional object is to provide a control circuit switch which hasbut two different types of contact elements although it may have bothnormally-.opcn and normally-closed contacts and is usableinterchangeably on both normally-open and normally-closed contactors ofwidely varying sizes and interrupting capacities.

The switch of this invention comprises in its preferred form aninsulating bracket arranged for attachment to the rockable armature of aclapper-type contactor and carrying within a continuously walled openingtherein a pair of identical conducting contact bridges biased apart by ahelical spring and insulated from each other by insulating membersinterposed between the spring and the respective contact bridges. Theinsulating members also serve to releasably retain the spring andbridges in cooperative relation within the opening. Each of the Contactbridges carries a pair of spaced contact buttons which, -upon rockingmovement of the armature, engage and disengage complementary stationaryContact buttons. Each of the stationary contact buttons is carried by acontact bracket detachably mounted on a stud. All of the stationarycontact brackets are identical whereas the studs, which extend outwardlyfrom the supporting structure for the contactor, may be of variouslengths dependingvupon the size and type of contactor and whether thecontact button associated with the stud is to be in normally-open ornormally-closed position with respect to its complementary movablecontact button. Each of the stationary coni tact ybrackets has contactbuttons on opposite faces thereof, respectively, which are selectivelyplaced into operative position vdepending upon whether the bracket ismounted on a stud which positions it for normally-open or normally-dosedoperation 0f its operative contact. rlihe life of each of the stationarycontact brackets is thereby doubled, merely by changing its positionfrom one stud to another.

Further objects and advantages of this inven tion will become apparentfrom the following de scription wherein reference is made to thedrawings in which:

Fig. 1 is a, side elevation of the improved control circuit switchmounted on the armature of a normally-open electromagnetic contactor;

Fig. 2 is a front elevation of the switch of Fig. l;

Fig. 3 is an exploded View and Fig. 4 is a side elevation of the movablecontact assembly;

Fig. 5 is a sectional view taken along the line 5-.5 of Fig. 4;

Fig. 6 is a side elevation of the switch or" Fig. i mounted on anormally-closed contactor; and

Fig.. 7 is a side elevation of a modiiied station=u ary contactassembly.

Referring to Figs. l and 2, an armature assembly I which may be part ofa normally-open electromagnetic contactor of the type, for example,described in L. A.A Troimov Patent No. 2,071,595 is suitably mounted forlimited rotary or rocking movement by having spaced bearing portions l lrotatably received on opposing end portions of a shaft i 2 carried by asupporting bracket I4 accurately positioned on and secured to aninsulating panel l5 as by a pair of horizontally spaced cap screws l5.The armature IU may carry the movable element of one or morenormally-open main circuit contacts lil. Upon energization of a windingIl, the armature IB rotates counter-clockwise (as viewed in Fig. l) fromthe normal or open position in which shown into engagement with amagnetic core cap I3 thus to close the main contacts, and upondeenergizaticn of the winding il returns as by gravity to its initialposition where it is stopped by engagement of shouldered surfaces i9 and20 formed on the armature I3 and on the support i4, respectively. Thecore cap i3 is maintained in a well-known manner a definite distancefrom the panel i5 and the surfaces I9 and 2i) may be finished orotherwise accurately determined whereby the opposite limits of movementof the armature i are accurately fixed.

The control circuit switch of this invention is adapted to be operatedby such movement of an armature member to open and close gaps in thecontrol circuits of a controller comprising the contactor or of arelated controller. The movable assembly of the control circuit switchcomprises a contact carrier 2l preferably molded from suitableinsulating material such as Bakelite and, as shown has a continuouslywalled transverse opening 22 formed in an enlarged end portion thereof.The reduced other end portion of the carrier 2l has opposing parallelsurfaces 23 and 24 which, in the embodiment shown, are normal to theplanes of opposing side walls 25a and 2519 (Fig. 3) of the opening 22and parallel to opposing end wall surfaces 26 of the opening. rlhe sidewall surface 25d of the opening 22 thus may be considered an end wall ofthe carrier 2l that terminates at overhanging end wall surfaces 2li ofthe opening. Preferably, the opening l22 is continuously walled, asshown, thus eliminating any possibility of breakage of the overhangingportions that define the end walls. The surface 24 is preferably acoplanar extension of one surface of the enlarged end portion whereasthe surface 23 is displaced from the plane of the opposite surface ofthe enlarged end portion by an angularly disposed surface 21. Thecarrier 2l is secured as by screws 28 to a projection 29 formed on thearmature lil and has its surface 23 in face-to-face contact with aninwardly extending and downwardly directed finished surface 30 of theprojection 23. As shown in Fig. 2, the armature lli may have aprojection 29 on each side whereby two identical control circuitswitches may be accommodated on a single contactor if desired.

The shaft l2 is accurately mounted in the support I4 which in turn isaccurately positioned on the panel l and thus the armature IU isconstrained to move in an accurately predetermined and consistentlymaintained path relative to the panel l5. Since the extent of movementof the armature I3 is limited by the fixed position of the core cap I8and the shouldered surface 2li and since the surface 23 of the carrier2l is accurately positioned on the finished surface 30 of the projection29, the opening 22 swings in an arc denitely predetermined in length aswell as in position with respect to the panel l5. As will becomeapparent, the accuracy of the length and location of this arc permitsthe elimination of adjustment features 4 heretofore generally providedin switches of this type.

As shown most clearly in Fig. 3, a pair of identical Contact bridges 32,a pair of identical retainer members 34, and a helical spring 35 areadapted to be received in the opening 22. Each of the contact bridges 32preferably comprises a flat strip cut from suitable electricalconducting strip stock, such as copper, of rectangular crosssection andeach has a central opening 3B and a pair of suitable contact buttons 38preferably of silver alloy welded or otherwise secured in axialalignment with each other on opposite faces. respectively. Each of thecontact buttons 38 has a peripheral side wall or edge which, in theillustrated embodiment, is of circular configuration, and, consideringeach pair of the contact buttons 38 on the same face of the bridges 32,the portions of the peripheral side walls thereof which face each otherconstitute shoulder areas which are spaced apart endwise of the bridgefrom, and face toward, each other.

The retainer members 34 are releasably engageable with the spring 35 andthe carrier 2| and constrain the contact bridges 32 and the spring inoperative position within the opening 22. Each of the retainer members34, which are preferably molded from suitable insulating material, has acentral portion 39 of reduced width defining a pair of opposing openslots 40. The slots 43 are intermediate of respective pairs of terminaltab portions 4| each of which has a. side wall 42 constituting ashoulder area and defining an end of the adjacent slot. A cylindricalboss 44 and a cylindrical boss 45 of lesser diameter are formed in axialalignment on opposing sides, respectively, of the central portion 39 ofeach of the retainers 34.

The movable portion of the switch is assembled by inserting a pair ofthe retainers 34 into the opening 22 and then rotating them until therespective bosses 44 are directed toward each other. The width of thecentral portion'39 is slightly less than the distance between the sidewalls 25a and 25h and the length of the slots 40 is slightly longer thanthe distance between the side surfaces of the carrier 2l so that each ofthe retainer members 34 may slide freely toward and away from each otherwithin the opening 22 while being releasably held therein by engagementof the walls 42 with adjacent opposing side surfaces of the carrier 2lnear the opening 22, With the retainers 34 disposed within the opening22, the spring 35 may be compressed and inserted between the retainers34 and then released to permit the respective bosses 44 to enter looselyinto opposing end portions of the spring 35. The peripheral side wall ofeach of the bosses 44 thereby constitutes a shoulder area whichreleasably engages the spring 35 and constrains the spring 35 in itsoperative position. Expansion of the spring 35 forces the retainers 34against the opposite end walls 25 of the opening 22, respectively.

By again compressing the spring 35, the upper one of the contact bridges32 may be inserted into the opening 22 between the top wall 26 and theuppermost retainer 34. When the opening 36 of this bridge is alignedwith the boss 45, release of the spring causes the boss 45 to enter theopening 36, which in effect provides aligned recesses in opposite facesof the bridge for receiving the boss 45, whereby the upper bridge 32 isreleasably held with opposite end portions thereof extending outwardlyfrom opposite sides of the carrier 2l. The lower one of the contactbridges 32 may likewise be inserted into the opening 22 between thebottom wall l25 and the lowermost retainer 34 the boss 45 of whichenters the opening 3G in the lower bridge when the lower bridge isproperlyl positioned and the spring 35 released, The width of thecontact bridges 32 issuiiiciently less than the width of the opening 22between the side walls 25 to permit the bridges to slide freely towardand away from each other, but these two dimensions are so related thatthe bridges are restrained from any extensive rotary movement about thecommon axis of the bosses '45. Thus the opposite side walls of each boss45 provide shoulder areas which are spaced apart endwise of the retainer34, and the opposite side Walls of each opening 36 provide shoulderareas engageable therewith for constraining relative movement of eachbridge 32 and its associated retainer 34. As best illustrated in Fig. 5,when the uppermost bridge 32 is in operative position, the shoulderareas which, in the form illustrated, are dened by the inner portions ofthe peripheral side walls of the contact buttons 3S on the under face ofthe uppermost bridge 32 are positioned for engagement with complementaryshoulder' areas defined by the opposite wall surfaces, respectively, ofthe uppermost retainer 34, and when the lowermost bridge 32 is inoperative position, the shoulder areas defined by the inner portions ofthe peripheral side walls of the contact buttons 38 on the upper face ofthe lowermost bridge 32 are positioned for engagement with complementaryshoulder areas defined by the opposite wall surfaces, respectively, ofthe lowermost retainer. Thus each retainer and its associated bridge areconstrained by shoulder areas from relative movement endwise of thebridges out of operating position. Accordingly each of the retainers 3cserves to transmit the biasing force of the spring 35 to its associatedone of the bridges 32, is constrained from movement out of the opening22 by engagement of its walls 42 with the side walls of the carrier 2|,constrains its associated one of the bridges 32 from movement out of theopening 22 by engagement between its end walls and the shoulder areasdened by a pair of the contacts 38 on that bridge, and constrains thespring 35 from movement out of the opening 22 by engagement between itsboss il and the spring. Preferably the length of the bosses 45 isapproximately the same as the thickness of the bridges 32 so that thetension of the spring 3'5 is approximately the same whether one or twoof the bridges are in operative position.

The stationary contact portion of the control circuit switch comprises aplurality of identical contact brackets 54 preferably formed of suitableelectrical conducting strip stock, such as copper, of rectangular crosssection. A lower end portion 55 (as viewed in Fig. 1) of each of thebrackets 54 is bent at a right angle to an intermediate portion 53 todenne an upwardly directed flat surface 5l', and the other or upper endportion 58 is bent at a lesser angle, preferably about forty-ve degrees,away from the intermediate portion 5B in the opposite direction. A pairof suitable contact buttons 59 which may be the same as the buttons 38are welded or otherwise secured in axial alignment with each other onopposite faces, respectively, of the portion 58 near the upper extremitythereof.

A pair of supporting studs 60 each for holding one of the contactbrackets 54 are suitably mounted in horizontal spaced relation on thepanel l5. As shown, each of the studs has an inner reduced portion 3lreceived into a complementary opening 62 in the panel and has an annularshoulder 64, defined by the junction of the reduced portion 3| and anenlarged cylindrical portion e5, in engagement with the front surface ofthe panel. An inner end portion of each of the studs E0 may be threadedto receive a retaining nut 65 and a conductor holding nut et. An outerend portion 69 of each of the studs et is of non-circular cross-section,preferably square, and defines a downwardly directed flat surface 'lilnormal to an end face 1I. One of the contact brackets 54 is secured tothe end face 1l of each of the studs 60 as by a screw 73 with thesurface 5l engaging the surface 18.

In like manner a pair of supporting studs T2 are mounted in horizontalspaced relation on the panel l5 above the studs 60 by insertion ofreduced portions 'f4 thereof into respective spaced openings 35. Thestuds l2 are preferably identical with the studs 60 except thatintermediate enlarged cylindrical portions 'F6 of the studs 12 areshorter than the corresponding portions 65 of the studs 6). An annularshoulder 11 on each of the studs 'l2 is held tightly against the paneli5 by a nut le threaded on an inner end portion of the studs and each ofthe studs 12 has a downwardly directed flat surface i9 on an outer endportion B3 of non-circular cross-section. The stud portions 55 and i6are preferably cylindrical, as shown, so as to prevent the piling ofdust thereon which may cause short circuits.

By positioning the pairs of openings 62 and 15 accurately with respectto the support I4, accurately determining the exposed lengths of studs53 and l2, and by making the brackets 54 uniform, all the contactbuttons 59 are in predetermined positions along the are of movement ofthe contact buttons 38 and have their respective axes substantiallytangential with respect to the arc of movement, thus renderingadjustment of the control circuit switch unnecessary.

When the armature I() is in its normal position as shown, the upwardlydirected contacts 38 on the upper contact bridge 32 are in engagementwith respective downwardly directed contacts 59 on the upper brackets 54and the upper bridge 32 has been displaced from its normal position tothe extent indicated (see broken Yline position, Fig. 4) against thebias of the spring 35 which maintains a definite contact pressure. Acircuit is thus completed between the spaced studs 'I2 through the uppercontact bridge 32. When this circuit is completed, the angularrelationship of the carrier 2! with respect to the portions 58 of theupper brackets 54 is such that the upper bridge 32 is turned slightlyabout its longitudinal axis with the engaged contacts 38 and 59 slightlyout of axial alignment. When the winding I1 is energized to move thearmature l0 to its closed position, the carrier 2i swings downwardlyabout the axis of the shaft i2 to cause engagement of the downwardlydirected contacts 38 on the lower bridge 32 with respectivecomplementary upwardly directed contacts 59 on the lower brackets 53.This completes a circuit between the studs 6c through the lower bridge32. Prior to engagement of the contacts 38 of the lower bridge 32 withthe respective contacts 59 on the lower brackets 54, the outer surfacesof the contacts 38 and 59- lie in parallel planes. After engagement ofthese contacts and while the spring 35 is being compressed, the lowercontact bridge 32 rotates slightly about its longitudinal axis in acounter-clockwise direction as viewed in Fig. 1. Thus a rollingengagement of the contact faces is obtained which improves their currentcarrying ability by removing any deposits on the contact surface andbringing the surfaces into close relationship. A similar rolling actionof the contact faces of the upper normally-closed contacts is obtainedwhen the armature I returns to its normal position.

It should be noted that the contact brackets 54 may be usedinterchangeably in normally open or normally-closed position dependingupon the position and length of the associated studs, and that wheninterchanged diiferent ones of the contact buttons 59 are placed intooperative position.

The insulating retainers 34 prevent any possibility of a circuit beingcompleted from a lower stud 50 to an upper stud 'l2 of opposite polaritythrough an arc drawn between separating contacts. Thus, in addition toserving as retainers for the bridges 32 and the spring 35, the retainers34 permit the stationary contact studs to be connected at eitherpolarity indiscriminately.

From the foregoing it is apparent that there is provided a controlcircuit switch of small and compact design yet one rugged enough towithstand severe service. Because of the provision of the opening 22,instead of an open slot, the bracket 2| has no reduced cross-sectionalareas subjected to excessive strain.

The contact bridges may be easily removed and replaced from the front ofthe contactor without the use of tools, and the brackets 54 and carrier2| are easily removed and replaced by the manipulation of screws theslotted heads of which face the front of the contacter. If only onecontact bridge 32 is required, the other may be removed withoutimpairing the operation. This is because the boss 4'5 which normallywould enter the opening 36 in the removed bridge bears against theadjacent end wall 26 of the opening 22 thereby maintaining the properlength of the spring 35.

In Fig. 6, the control circuit switch is shown as used on anormally-closed contactor having an armature 82 mounted for limitedrotary movement about a shaft 83 carried by a bracket 84 secured to apanel 85. carry the movable element of one or more normally-closed maincircuit contacts (not shown). Upon energization of a winding 86, thearmature 82 rotates clockwise from the normal or closed position inwhich shown into engagement with a magnetic core cap 8l thus to openmain contacts (not shown), and upon deenergization of the winding 86returns as by the force of a spring (not shown) to its initial positionagainst a suitable stop 89.

The armature 82 is provided with a projection 90 having an inclinedfinished Surface 9|. The carrier 2| of the movable contact assembly issecured to the projection 90 with its surface 24 in face-to-face contactwith the surface 9| and the contacts 38 thereof swing in a predeterminedarc upon rocking action of the arma-ture 82. Pairs of horizontallyspaced upper studs 92 and lower studs 94 are carried by the panel 85 andeach of these studs receives on its outer end one of the contactbrackets 54. In Fig. 6, each of the brackets 54 is inverted from theposition in which shown in Figs. 1 and 2 with its flat surface portion51 engaging a iiat surface 95 formed The armature 82 may r on the upperside of the outer end portion of each of the studs 92 and 94.

When the armature 82 is in normal position, the lower contact bridge 32as viewed in Fig. 6 completes a circuit between the studs 94 and, uponenergization of the winding 86, this circuit is interrupted anda circuitcompleted between the upper studs 92 through the other one of thecontact bridges 32. Interchanging the contact brackets 54 between upperand lower studs puts different ones of the contact buttons 59 intooperative position.

In the modified stationary contact assembly of Fig. 7, a plurality ofidentical contact brackets |0| similar to the brackets 54l are suitablymounted in spaced relation on the outer ends of suitable studs |02,respectively, al1 of which are of the same length. A pair of contactbuttons |04 similar to the buttons 59 are secured on opposite faces,respectively, of the outer end portion of each of the brackets |0| andare displaced axially from each other longitudinally of their respectivebrackets. When a pair of the brackets |0| are in mounted position onvertically aligned studs |02, respectively, as viewed in Fig. 7, theinner contact button |04 on the uppermost bracket |0| is spaced from andfaces the outer contact button on the lowermost bracket. Uponinterchanging the positions of lowermost and uppermost brackets |0|, theouter contact button |04 on the bracket |0| that before the interchangewas the uppermost now faces the inner contact button on the bracket thatbefore the interchange was the lowermost. By proper selection of theangle of bend of the brackets |0| and the positions of the contactbuttons |04, the respective axes of those contact buttons |04 which faceeach other may be made substantially tangent to an arc defined byswinging movement of the movable contact buttons 38 carried by thecarrier 2|.

Having thus described my invention, I claim:

1. An electric switch comprising a contact carrier having a guide wallsurface and spaced overhanging wall surfaces extending outwardly inface-to-face spaced relation with each other from opposite end portions,respectively, of the guide wall surface, a conducting contact bridgereceived in the space between the overhanging wall surfaces and havingopposite end portions extending outwardly beyond the opposite edges ofthe guide wall surface, said contact bridge slidably engaging said guidewall surface for free movement there along in a path toward and awayfrom said overhanging wall surfaces while being constrained by saidguide wall surface from extensive rotary motion about an axis normal tosaid overhanging wall surfaces, a spring between the overhanging wallsurfaces for normally biasing said contact bridge against one of saidoverhanging wall surfaces, a member movable along said path andinterposed between said spring and said bridge and transmitting thebiasing force of the spring to the bridge, means on the memberdetachably engageable with the carrier for constraining said member insaid path, and said member and contact bridge having mutually detachablyengageable portions which constrain said contact bridge in operativeposition in said path.

2. An electric switch as in claim 1 characterized in that said member isof insulating material and said spring is of electrically conductivematerial.

3. An electric switch comprising a contact carrier provided with avcontinuous walled opening having elongated parallel'side wall surfacesand opposing end wall surfaces, -a conducting contact bridge received insaid openingV with opposite end portions extending'outwardlyY from saidopening on opposite sides of said carrier, said contact bridge slidablyengaging said side wall surfaces in a path for movementl along said sideWall surfaces toward and away from saidend wall surfaces while beingconstrained by said side Wall surfaces from extensive rotary motionabout an axis normal to said end wallsurfaces, a spring between said endwall surfaces for normally biasing said contact bridge against one ofsaid end wall surfaces, a member movable along said path and interposedbetween said spring and said bridge and transmitting-the biasing forceof the spring to the bridge, means on the member detachably engageablewith the carrier for constraining said memberV from movement out of saidopening, and said member and contact bridge having mutually detachablyengageable portions which constrain -saidcontact bridge in said path.

4. An electric switch according to claim 2 having elongated parallelside wall surfaces and opposing end wall surfaces, a conducting contactbridge having an aperture and received in said opening with opposite endportions extending outwardly from said opening on opposite sides of saidcarrier, said contact bridge slidably engaging said side wall surfacesfor free movement along said side wall surfaces toward and away fromsaid end wall vsurfaces while being restrained by said sidewall'surfacesfrcm extensive rotary motion about an axis normal to saidend wall surfaces', a helical spring within said opening normallybiasing saidv contact bridge against one of said end wall surfaces, aretainer member releasably held in said opening intermediate of saidcontact bridge and said spring and having opposing bosses receivedrespectively within the helix of said spring and 'in said aperture,whereby said contact bridge and said spring are releasably constrainedagainst displacement from said opening.

6. The electric switch of claim 5`characterized in that a secondretainer member is releasably held in said opening intermediate of theother one of said end wall surfaces andl said spring, said retainermembers being identical and one of the bosses on said secondretainenbeing received within the helix of said spring, and the otherone of the bosses of said'second retainer and the boss of said rst namedretainerin said aperture each having an axial length relative to thethickness of said contact bridge such that upon insertion of a secondidentical contact bridge in said opening with said otherone of thebosses of said second retainer received 1in' the aperture of theidentical bridge, the tension of said spring remains substantiallyunchanged.

7. The electric switch ofclaim 6character ized in that said secondcontact bridge is inserted between said Second retainermember and saidother one of said end wall surfaces with said other one of the bosses ofsaid secondretainer received in the aperture of the second bridge, andsaid retainer members are of insulating material and electricallyinsulate said contact bridges, r-e- Spectively, from said spring andfrom each other.

8'. An electric vswitch comprising ra pair of identical rigid contactbrackets Aeach" having' a pair of' contact buttons, said buttons of eachbracket being secured on opposite sides .thereof respectively, meansdetachably holding said brackets in xed spaced relation with one of thecontact buttons on one of the brackets spaced from andfacing one of thecontact buttons on the other one of the brackets, and said other contactbuttons being so positioned on their respective brackets that, uponinterchanging the position of the two brackets, the other button'of eachbracket interchanges position with said one button of the other bracket.

9. The 'switch` of' claim 8 vcharacterized-in that the contact buttonsof each bracket are disposed in axial alignmentr with each other.`

10. An electric switch comprising a movable contact means movable alonga xed Vpath beltween limits, a pair of identicall contact brackets eachhaving a pair of contact buttons, said. but'- tons of each bracket beingsecured on opposite sides thereof respectively, means detachably holdingsaid brackets in spaced xed relationwith one contact button on one ofthe brackets` facingY one of the contact buttons on the other one of thebrackets with the facing contact buttons .disposed at said limitsrespectively of said path of movement, and saidother contact buttonsbeing so positioned upon their respective brackets that they face eachother at said limits respectively upon interchanging the positions ofAsaid brackets.

11. An electric switch comprising a movable contact means movable alonga xed path be-v tween limits, a pair of identical contactbrackets eachhaving, endwise of the bracket, an innermost and an outermost contactbutton, said contact buttons being secured on opposite sidesrespectively, of their respective brackets, andY means detachablyholding said brackets in spaced xed relation with the innermost contactbutton on one of the brackets facing the Voutermost contact button onthe other one of the brackets `with the facing contact buttons disposedat said limits respectively of said path of movement, whereby said othercontact button of each bracket interchanges position with said onebutton of the other bracket upon interchanging thepositions of saidbrackets.

12. An. electric switch comprising a pair of identical contact bracketseach having a pair of contact buttons, said buttons of each bracketbeing secured on opposite sides thereof respectively, means detachablyholding said brackets in spaced relation with one of the contact buttonson one of the brackets spaced from and facing one of the contact buttonson the other one of the rackets and with the respective axes of thefacing contact buttons approximately tangent to a common circular arc atpredetermined spaced points respectively on said arc, and said othercontact buttons being so positioned upon their respective brackets that,upon interchanging said brackets, said other contact buttons are spacedfrom and face each other with their respective axes approximatelytangent to said arc at said predetermined points, respectively.

13. The electric switch of claim 12rcharacter ized in that said contactbuttons when in'facing position have their respective axesvat an angleto the vertical.

14. An electric switch comprising a plurality of identical contactbrackets each having a pair of contact buttons, said buttons of eachbracket being secured on opposite sides thereof, spaced mounting meansfor a rst pair of said brackets, respectively, detachably holding saidfirst pair of bracketsv in spaced relation with respect to each otherwith one contact button on one of said brackets of said first pairfacing one contact button on the other one of said brackets of 'saidfirst, pair approximately along a nonvertical axis, spaced mountingmeans for a second pair of said brackets, respectively, detachablyholding said second pair of brackets in 'spaced relation with respect toeach other with one contact button on one of the brackets of said secondpair facing one contact button on the other of the brackets of saidsecond pair along a second axis approximately parallel to the firstaxis, a movable contact means movable substantially along said axes forbridging between said one contact button on said one bracket of saidfirst and said one bracket of said second pair of brackets, and saidother contact buttons being positioned on said brackets, respectively,so that, upon interchanging brackets having contact buttons in the sameaxis, said other contact buttons on said brackets face each other alongsaid last mentioned axis.

15. An electric switch comprising a plurality of identical contactbrackets each having a pair of contact buttons` said buttons of eachbracket secured on opposite sides thereof, spaced mounting means for afirst pair of said brackets, respectively, detachably holding said firstpair of brackets in spaced relation with respect to each other with onecontact .button on one of said `brackets of said Vfirst pair facing onecontact button on the other one of said brackets of said first pairapproximately along a non-vertical axis, spaced mounting means for asecond pair of said brackets, respectively, detachably holding saidsecond pair of brackets in spaced relation with respect to each otherwith one contact button on one of the brackets of said second pairfacingl one contact button on the other of the brackets of said secondpair along a second axis approximately parallel to the first axis, apair of conducting contact bridges each having contact end portions atopposite ends thereof, a movable contact carrier movable between andsubstantially parallel to said axes and defining an opening slidablyreceiving said contact bridges in spaced apart relation with one pair ofthe contact end portions extending outwardly from said opening anddisposed in one of said axes in alignment with the contact buttonsthereof and the other pair of contact making end portions extendingoutwardly from said opening and disposed in the other of said axes inalignment with the contact buttons thereof, a metal spring biasing saidbridges apart, insulating retainers between said bridges respectivelyand said spring and shaped to hold said spring and bridges in assembledrelation in said opening, and means for moving said carrier from aposition wherein one of said bridges forms an electrical connectionbetween two of said contact buttons to a position wherein the other ofsaid contact bridges forms an electrical connection between the othercontact buttons which face said two contact buttons.

V16-l An electric switch comprising a contact carrier provided with acontinuous walled opening having elongated parallel side Wall surfacesand opposing end wall surfaces, a pair of conducting contact bridgesreceived in said opening, each with opposite end portions extendingoutwardly from said opening on opposite sides of said carrier, saidcontact bridges slidably engaging said side wall surfaces for movementalong said side wall surfaces toward and away from said end Wallsurfaces while being restrained by said side wall surfaces fromextensive rotary motion about an axis normal to said end wall surfaces,a metal spring in said opening and between said contact bridges andnormally biasing said contact bridges against said end wall surfaces,respectively, insulating means interposed between said spring and saidcontact bridges, respectively, and each releasably engaging the springand carrier, means on the insulating means engaging the carrier forconstraining the insulating means from movement out of the opening whenin normal operating positions, means on each insulating means engagingits associated contact bridge and constraining its associated contactbridge from movement out of the opening, means on the insulating meansengaging the spring and constraining said spring to operative positionin said opening and each of said insulating means electricallyinsulating its associated contact bridge from said spring.

17. An electric switch comprising a contact carrier provided with acontinuous walled opening having elongated parallel side wall surfacesand opposing end wall surfaces, a pair of elongated conducting contactbridges received in said opening each with opposite end portionsextending outwardly from said opening on opposite sides of said carrierand having shoulder areas spaced apart endwise of the bridge from, andfacing toward, each other, said contact bridges slidably engaging saidside wall surfaces for movement along said side vwall surfaces towardand away from said end wall surfaces while being restrained by said sideWall surfaces from extensive rotary motion about an axis normal to saidend wall surfaces, a metal spring in said opening between said contactbridges and normally biasing said contact bridges against said end wallsurfaces, respectively, and insulating retaining means interposedbetween said spring and said contact bridges, respectively, and havingspaced shoulder areas releasably engaging said shoulder areas,respectively, of said respective contact bridges for constraining thebridges in operative position within said opening, and having shoulderareas releasably engaging the spring and constraining said spring tooperative position, and having additional shoulder areas releasablyengaging the carrier and constraining the insulating means from movementout of said opening.

18. Anelectric switch according to claim 17 further characterized inthat said additional shoulder areas are wall surfaces of terminal tabportions on each insulating means which engage respective outer surfaceareas of the carrier adjacent the opposite ends of the opening,

19. An electric switch according to claim 17 characterized further inthat said spring has boss receiving openings at opposite ends,respectively, and said shoulder areas engaging the spring are side wallportions of bosses on the insulating means, respectively, and arereceived in said boss receiving openings, respectively.

20. An electric switch comprising a contact carrier provided with acontinuous walled opening having elongated parallel side Wall surfacesand opposing end wall surfaces, a pair of elon- 13 gated conductingcontact bridges received in said opening each with opposite end portionsextending outwardly from said opening on opposite sides of said carrierand having shoulder areas spaced apart endwise of the bridge from, andfacing toward, each other, said contact bridges slidably engaging saidside wall surfaces for movement along said side wall surfaces toward andaway from said end Wall surfaces while being constrained by said sidewall surfaces from extensive rotary motion about an axis normal to saidend wall surfaces, a metal spring in said opening between said contactbridges and normally biasing said contact bridges against said end wallsurfaces, respectively, and insulating retaining the insulating meansfrom movement out of said opening.

EVERETT E. NOYES.

REFERENCES CITED The following references are of record in the le ofthis patent:

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